Foil and Heat Treating

A

Augus7us

Joined
Oct 9, 2014
Messages
694
Hey All,

This question may have an obvious answer but it is eluding me. So when I picked up my kiln a few months ago in anticipation of its arrival I picked up some industrial foil. Having read the instructions and watched countless videos I was ready to go. Had my quench oil ready, kiln was burnt in, knives ready to go all wrapped in foil (they were 1084). Alarm went off pulled the blades out and realised I hadn't thought through how to quench with foil wrapped around the blade in all the excitement... I ripped it off as quick as possible and needless to say the quench didn't take and I said screw it and heat treated again without foil.

My question is can you actually use it and quench in oil or water? I know you can but it would seem the foil would act as an insulator and cause the quench to fail. Is it only for air quench? Or when annealing or normalizing?

I've since bought the anti scale powder but I've been curious if anyone uses foil when quenching and how!

Thanks

-Augus7us
 
Foil is normally saved for the air hardening steels, and anti scale, or nothing on simple steels like 1084. The air hardening, high alloy steel require a long soak at a high heat, and therefore require protection from the oxy, and they are a slow enough quench, that the foil can be left on, or cut off and a cooled, without effecting the quench/hardening.

Is you leave a little meat on your 1084 blades, you can just grind off the decarb.
 
The pearlite nose on carbon steels is too narrow to allow foil packets for HT. The steel needs to cool down below 1000F in .5 to 2 seconds. Also, the temperature range used for carbon steel is between 1450 and 1525F, which does not need oxygen protection for the 1-10 minute soak time used.
Only air cooling steels and high alloy steels like stainless, need oxygen protection. These HT at 1700-2100F and have hold times of 30-45 minutes. In these steels the pearlite nose is very wide, and there are several minutes ( not seconds) for the steel to cool down past 1000F. The blade also does not get quenched in liquid, so it is normally left in the packet and either air cooled, or more popularly - cooled between quench plates ( thick aluminum plates in a clamping device of some sort).
 
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Thanks Stacy and Cody. I sort of figured that was the case since I couldn't think of any logical way you were going to get the foil off and dunk the blade in that short of a time period. Fortunately it was cheap and I'm happy to experiment so eventually I'll get some stainless and it will get used. I'll likely slice a finger open again as well. Such is knifemaking I reckon ;)
 
I always wear thin leather gloves when working with foil... ask me how I learned that :D


Pablo
 
Good point PEU,
Advice to new users of foil....it is similar to the stock they make razor blades from....just thinner. It will cut you BAD if not careful. Gloves are a virtual requirement unless you really like to bleed. After HT it is has also been hardened...and will cut you worse. Best way to open the packets is to snip the end off with a heavy pair of shop scissors.
 
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